Study of supramolecular frameworks having aliphatic dicarboxylic acids, N,N′-bis(salicyl)ethylenediamine and N,N′-bis(salicyl)butylenediamine

• Six new salts of dicarboxylic acids with N,N′-bis(salicyl)alkylenediamines.
• Detailed X-ray crystallographic study for salts.
• Comparison of solid and gaseous phase structure for salts.
• Curve fitting analysis between experimental and theoretical values.

The reaction of bases (L1 and L2) (where L1 = N,N′-bis(salicyl)ethylenediamine, L2 = N,N′-bis(salicyl)butylenediamine) with dicarboxylic acids [adipic acid (1,6-Hexanedioic acid, AA), pimelic acid (1,7-Heptanedioic acid, PA) and suberic acid (1,8-Octanedioic acid, SUA] yielded the corresponding six new ionic salts viz., [1/2L1H+⋅1/2AA−⋅1/2AA] (1), [2 × 1/2L1H+⋅PA2−⋅CHCl3] (2) [1/2L1H+⋅1/2SUA−] (3), [1/2L2H+⋅1/2AA−⋅2CH3OH] (4), [1/2L2H+⋅1/2PA−] (5) and [1/2L2H+⋅1/2SUA−] (6), respectively. Theses salts were characterized by elemental analysis, FT-IR, NMR, X-ray crystallography, and theoretically by means of Gaussian 09. The X-ray crystallographic studies revealed that the proton transfer occurred from acid to base. It also demonstrated that different type of hydrogen bond interactions between cations and anions were responsible for the supramolecular frameworks. The optimized structures of these salts were calculated in terms of the density functional theory. The curve fitting analysis between experimental and simulated data of structural parameters was done, and found statistically close. The orientation of molecules was remained same in both the gas and solid phases. The thermal studies of these salts were investigated by TG–DTG.

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